This invention relates to child-resistant door locks. More particularly, it refers to a magnetically controlled means for opening automatic door locking mechanisms.
A variety of locking mechanisms exist for use in conjunction with sliding doors such as glass patio doors. These devices include bars, pins, track-mounted stops and latch-keeper devices. The bar-type locking mechanism prevents the door from sliding by spanning the distance between the edge of the door and the door jamb, thereby reacting to a door opening force in compression. Pins prevent the door from sliding by pinning the door to a stationary member such as the door frame of the opposite door, thereby reacting to a door opening force in shear. Track-mounted stops are secured to the track on which the sliding door glides and block the door from sliding along the track once the door engages the stop. Finally, latch-keeper combinations consist of a latch in the door frame and a keeper in the door jamb which engage together to secure the door frame to the door jamb.
In the case of bar-type, pin-type and track-mounted stop configurations, it is not possible to lock or unlock the door from the face of the door opposite the face on which the pin-type, bar-type or track-mounted stop is installed. In the case of latch-keeper mechanisms, the locking and unlocking means is normally found at an elevation accessible to small children and these mechanisms are not normally constructed to prevent unlocking from the interior of the building in which the door is installed. In more sophisticated versions of these types of mechanisms, key actuated latch-keeper lock mechanisms may be employed. This type of lock mechanism is expensive, is difficult to add to pre-existing door installations, and requires permanent modifications to the door. Pin-type and bar-type locking devices also require permanent door modifications to doors on which they are installed.
The present invention is intended to overcome the deficiencies of the prior art. The door lock of this invention can be easily installed by the door owner without the use of tools and requires no permanent modification to the door on which it is installed. The door lock of this invention may be removed easily from the door when there is no more need for it. On the side of the door on which the inventive locking device is installed, it can be opened by anyone able to reach to the elevation of the device as installed. On the opposite face of the door, typically outside the building in which the door is installed, the user grasps a magnetic key stored at a high elevation near that door face and places the key against the outer surface of the door, thereby causing the latch to rotate into the unlocked position as will be described in greater detail hereinafter.
The following prior art is known to Applicant:
U.S. Pat. No. 4,848,812 to Slaughter discloses a concealed safety lock having a bolt in the form of a cylindrical magnet that may be moved through the use of a magnetic key.
U.S. Pat. Nos. 4,919,464 and 5,076,623, both to Richards, disclose latch mechanisms for use, for example, in holding a door leaf closed and include a pivotable assembly carrying a magnet that holds a magnetically attractive material attached to the door leaf closely adjacent thereto in one position thereof, and is pivoted away from that position responsive to close proximity of a magnetic key, thereby allowing the door leaf to be opened.
U.S. Pat. No. 5,188,405 to Maccaferri discloses a locking device for a latch similar to that of the Richards patents but including the further provision of a locking mechanism designed to hold the latch in an open position.
U.S. Pat. No. 5,485,733 to Hoffman discloses a concealed magnetic lock for cabinet closure that includes a pivotable magnetic piece biased in one direction through a built-in magnet and pivotable away from that position through the use of a magnetic key.
The present invention differs from the teachings of these patents as contemplating a latch designed to move and lock through the force of gravity to a latched position automatically and may be moved to an unlatched position through the repelling force between a latch-mounted magnet and a magnet mounted in a key.